The present invention is related to a locating/controlling structure for telescopic tube, and more particularly to a locating/controlling structure for effectively locating a telescopic tube with elliptic cross-section.
FIG. 6 shows a conventional locating structure for telescopic tube with elliptic cross-section. One end of the outer tube 81 of the telescopic tube 8 is provided with an outer tube fixing seat 82. A base seat 83 is fitted through the outer tube fixing seat 82, whereby the base seat 83 can be rotated thereabout. An elongated bar 84 with square cross-section is connected on the base seat 83. A linking seat 85 is fitted on the elongated bar 84. The linking seat 85 is formed with a square hole 851 through which the elongated bar 84 is passed. When turning the elongated bar 84, the linking seat 85 is driven and rotated along with the elongated bar 84.
The linking seat 85 has a projecting post 852. One end of the projecting post 852 adjacent to the linking seat 85 has an eccentric section 853. An eccentric block 86 with elliptic cross-section is fitted on the eccentric section 853. The other end of the projecting post 852 is formed with an annular hook section 854.
One end of the inner tube 87 fitted in the outer tube 81 is provided with an inner tube fixing seat 88 having a through hole 881 through which the projecting post 852 of the linking seat 85 is fitted. The hook section 854 of the projecting post 852 is engaged with and located on the inner tube fixing seat 88, whereby the linking seat 85 can be rotated within the inner tube fixing seat 88.
According to the above structure, by means of turning the base seat 83, the elongated bar 84 is driven and rotated. At this time, the elongated bar 84 synchronously drives the linking seat 85 to rotate. The eccentric section 853 of the linking seat 85 is eccentrically rotated to push the eccentric block 86 against the inner wall face 811 of the outer tube 81 as shown in FIGS. 7 and 8. By means of the frictional force exerted by the eccentric block 86 against the inner wall face 811, the inner tube 87 is locked with the outer tube 81.
However, the eccentric block 86 should be able to move within the outer tube 81. Therefore, the circumferential length of the eccentric block 86 must be shorter than the circumferential length of the inner wall face 811 of the outer tube 81. In other words, the eccentric block 86 must be a smaller ellipse. Furthermore, the eccentric block 86 is driven by the eccentric section 853 to eccentrically rotate. Therefore, only the outer face of one side of the eccentric block 86 is deflected to about against the inner wall face 811 of the outer tube 81 as shown in FIG. 8. As a result, the smaller elliptic eccentric block 86 only contacts with the inner wall face 811 of the larger outer tube by a small contacting area. Therefore, the locating force is insufficient.
The outer face of one side of the eccentric block 86 is deflected to abut against the inner wall face 811 of the outer tube 81 so as to provide a locating force. However, the inner wall face 811 exerts a reaction force onto the inner tube 87 to push the same toward the other side as shown in FIG. 7. Therefore, the inner tube 87 is deflected from the outer tube 81 and unevenly suffers force. This affects the locating strength of the inner tube 87 and the outer tube 81. Moreover, with one side of the inner tube 87 deflected to abut against the outer tube 81, when using the telescopic tube, in the case that the inner tube 87 suffers a greater force, the inner tube 87 will be deflected and inclined from the outer tube 81 as shown in FIG. 9. In the case that the telescopic tube is connected with a cutting or shearing tool, the strength and application force of the inner and outer tubes 87, 81 will be affected.
It is therefore a primary object of the present invention to provide a locating/controlling structure for telescopic tube. A rotary button is rotatably disposed at one end of the outer tube. The rotary button is connected with an elliptic rod passing through the outer tube. An inner tube is telescopically nested in the outer tube. One end of the inner tube fitted in the outer tube is provided with a cock body formed with a central circular hole through which the elliptic rod is passed. The cock body has a stop section protruding from the inner tube. The stop section is formed with two radially opposite receptacles. A movable block is disposed in each of the receptacles. Each movable block has a contacting face complementary to the inner circumference of the outer tube. When the rotary button is turned to drive the elliptic rod to rotate about the axis thereof, due to the different diameters of the elliptic rod, the elliptic rod pushes the two movable blocks to synchronously radially outward move, whereby the contacting faces of the movable blocks press and abut against the inner circumference of the outer tube to firmly locate the inner and outer tubes.
It is a further object of the present invention to provide the above locating/controlling structure for telescopic tube, in which the contacting face of each movable block is formed with slipproof ribs so as to increase the frictional force between the contacting faces and the inner circumference of the outer tube and thus enhance locating effect for the inner and outer tubes.
It is still a further object of the present invention to provide the above locating/controlling structure for telescopic tube, in which rotary button is rotatably connected with the handle to form an assembly. Therefore, the locating/controlling structure includes fewer components and can be more quickly assembled so as to reduce the problem of tolerance of clearance caused by assembly of numerous parts. Accordingly, the reliability of the telescopic tube is increased and the processing cost is lowered.